Various bismaleimides, such as N,N'-(m-phenylene)bismaleimide, have been added to rubber to modity its properties. For example, in U.S. Pat. No. 4,803,250 various bismaleimides are added to rubber in combination with sulfur and accelerators to improve the resistance to reversion in the vulcanization step. Whereas, bismaleimides can be used to improve reversion resistance, the present inventors have discovered that a new and useful modified form of such bismaleimides are superior in improving the tear resistance of rubber. Since many rubber products are subjected to a harsh environment in use, any improvement in the tear resistance of such rubbers further contributes to the longevity and structural integrity of products made therefrom, including tire treads.